Don't fire unexpected callbacks from SASL threads
Don't fire unexpected callbacks from SASL threads

Summary:
So I think here is the problem:
- Request #1 fires, SASL times out, we fall back the channel to insecure mode and send a request.
- The request comes back, we detach the event base from the channel and put it in the idle pool.
- At this point the SASL thread could still be chugging along trying to talk to the KDC, etc.
- Request #2 fires, takes the channel off the idle pool, attaches another evb to it. This request is now in flight
- The SASL threads finally completes, and since we now have a valid evb on the channel it fires a saslSendServer (which schedules another timeout on the channel)
- Response #2 comes back, we try to detach from the channel but can't since there is a request in progress and a timeout set.

Test Plan: unit tests

Reviewed By: mshneer@fb.com

Subscribers: alandau, bmatheny, mshneer, wstefancik

FB internal diff: D1635252

HankFaan/fbthrift,chjp2046/fbthrift,uber/fbthrift,SergeyMakarenko/fbthrift,raphaelamorim/fbthrift,jesboat/fbthrift,sinjar666/fbthrift,sinjar666/fbthrift,raphaelamorim/fbthrift,getyourguide/fbthrift,facebook/fbthrift,uber/fbthrift,facebook/fbthrift,kangkot/fbthrift,uber/fbthrift,getyourguide/fbthrift,LinusU/fbthrift,uber/fbthrift,kangkot/fbthrift,jesboat/fbthrift,getyourguide/fbthrift,kangkot/fbthrift,LinusU/fbthrift,HankFaan/fbthrift,LinusU/fbthrift,sinjar666/fbthrift,Orvid/fbthrift,maxwell-demon/fbthrift,getyourguide/fbthrift,getyourguide/fbthrift,soumith/fbthrift,raphaelamorim/fbthrift,Orvid/fbthrift,project-zerus/fbthrift,fengshao0907/fbthrift,LinusU/fbthrift,project-zerus/fbthrift,Orvid/fbthrift,maxwell-demon/fbthrift,jesboat/fbthrift,jesboat/fbthrift,maxwell-demon/fbthrift,uber/fbthrift,kangkot/fbthrift,maxwell-demon/fbthrift,HankFaan/fbthrift,LinusU/fbthrift,guker/fbthrift,chjp2046/fbthrift,LinusU/fbthrift,facebook/fbthrift,fengshao0907/fbthrift,fengshao0907/fbthrift,soumith/fbthrift,project-zerus/fbthrift,chjp2046/fbthrift,jesboat/fbthrift,sinjar666/fbthrift,SergeyMakarenko/fbthrift,fengshao0907/fbthrift,kangkot/fbthrift,getyourguide/fbthrift,guker/fbthrift,SergeyMakarenko/fbthrift,project-zerus/fbthrift,getyourguide/fbthrift,uber/fbthrift,soumith/fbthrift,guker/fbthrift,project-zerus/fbthrift,jesboat/fbthrift,sinjar666/fbthrift,raphaelamorim/fbthrift,facebook/fbthrift,fengshao0907/fbthrift,fengshao0907/fbthrift,SergeyMakarenko/fbthrift,kangkot/fbthrift,jesboat/fbthrift,chjp2046/fbthrift,raphaelamorim/fbthrift,project-zerus/fbthrift,guker/fbthrift,soumith/fbthrift,sinjar666/fbthrift,uber/fbthrift,uber/fbthrift,project-zerus/fbthrift,HankFaan/fbthrift,raphaelamorim/fbthrift,soumith/fbthrift,fengshao0907/fbthrift,fengshao0907/fbthrift,Orvid/fbthrift,guker/fbthrift,soumith/fbthrift,sinjar666/fbthrift,HankFaan/fbthrift,soumith/fbthrift,maxwell-demon/fbthrift,chjp2046/fbthrift,soumith/fbthrift,uber/fbthrift,SergeyMakarenko/fbthrift,SergeyMakarenko/fbthrift,jesboat/fbthrift,project-zerus/fbthrift,chjp2046/fbthrift,chjp2046/fbthrift,soumith/fbthrift,SergeyMakarenko/fbthrift,Orvid/fbthrift,maxwell-demon/fbthrift,uber/fbthrift,Orvid/fbthrift,SergeyMakarenko/fbthrift,kangkot/fbthrift,Orvid/fbthrift,chjp2046/fbthrift,HankFaan/fbthrift,HankFaan/fbthrift,sinjar666/fbthrift,SergeyMakarenko/fbthrift,soumith/fbthrift,sinjar666/fbthrift,sinjar666/fbthrift,fengshao0907/fbthrift,HankFaan/fbthrift,maxwell-demon/fbthrift,jesboat/fbthrift,project-zerus/fbthrift,maxwell-demon/fbthrift,getyourguide/fbthrift,jesboat/fbthrift,HankFaan/fbthrift,LinusU/fbthrift,facebook/fbthrift,Orvid/fbthrift,raphaelamorim/fbthrift,facebook/fbthrift,kangkot/fbthrift,LinusU/fbthrift,jesboat/fbthrift,chjp2046/fbthrift,getyourguide/fbthrift,SergeyMakarenko/fbthrift,guker/fbthrift,project-zerus/fbthrift,facebook/fbthrift,Orvid/fbthrift,maxwell-demon/fbthrift,HankFaan/fbthrift,SergeyMakarenko/fbthrift,Orvid/fbthrift,raphaelamorim/fbthrift,jesboat/fbthrift,project-zerus/fbthrift,SergeyMakarenko/fbthrift,guker/fbthrift,project-zerus/fbthrift,kangkot/fbthrift,LinusU/fbthrift,kangkot/fbthrift,LinusU/fbthrift,fengshao0907/fbthrift,guker/fbthrift,sinjar666/fbthrift,facebook/fbthrift,guker/fbthrift,chjp2046/fbthrift,chjp2046/fbthrift,raphaelamorim/fbthrift,maxwell-demon/fbthrift,getyourguide/fbthrift,getyourguide/fbthrift,chjp2046/fbthrift,facebook/fbthrift,raphaelamorim/fbthrift,fengshao0907/fbthrift,uber/fbthrift,LinusU/fbthrift,raphaelamorim/fbthrift,guker/fbthrift,soumith/fbthrift,HankFaan/fbthrift,Orvid/fbthrift,maxwell-demon/fbthrift,guker/fbthrift,getyourguide/fbthrift,uber/fbthrift,kangkot/fbthrift